A Composite Service Provision Method Based on Novel Node Model in Mobile Ad Hoc Networks

Composite service provision in mobile ad hoc networks encounters great challenges and its success rate is not satisfactory because the nodes' locations are dynamic and the nodes maybe unavailable at any time.Composite service is built through the service composition.In mobile ad hoc networks,the factors influencing the success rate of service composition are mainly the number of nodes and the time spent for the composition.The node's failure probability is proportional to the length of time the node exist in the networks.In order to improve the success rate of service composition,we take several measures.First,we split the service requirement into several segments and cluster the nodes,so that the nodes' waiting time for service composition can be reduced.Second,we propose a new node model of "one node contains multiple services" in mobile ad hoc networks.Using this type of nodes model,the number of nodes required for service composition can be reduced.These means can increase the success rate of service composition.

Range-Based Localization in Wireless Networks Using Density-Based Outlier Detection

Node localization is commonly employed in wireless networks. For example, it is used to improve routing and enhance security. Localization algorithms can be classified as range-free or range-based. Range-based algorithms use location metrics such as ToA, TDoA, RSS, and AoA to estimate the distance between two nodes. Proximity sensing between nodes is typically the basis for range-free algorithms. A tradeoff exists since range-based algorithms are more accurate but also more complex. However, in applications such as target tracking, localization accuracy is very important. In this paper, we propose a new range-based algorithm which is based on the density-based outlier detection algorithm (DBOD) from data mining. It requires selection of the K-nearest neighbours (KNN). DBOD assigns density values to each point used in the location estimation. The mean of these densities is calculated and those points having a density larger than the mean are kept as candidate points. Different performance measures are used to compare our approach with the linear least squares (LLS) and weighted linear least squares based on singular value decomposition (WLS-SVD) algorithms. It is shown that the proposed algorithm performs better than these algorithms even when the anchor geometry about an unlocalized node is poor.

A Layer-Cluster Key Agreement Protocol for Ad Hoc Networks

Mobile ad hoc networks create additional challenges for implementing the group key establishment due to resource constraints on nodes and dynamic changes on topology. The nodes in mobile ad hoc networks are usually low power devices that run on battery power. As a result, the costs of the node resources should be minimized when constructing a group key agreement protocol so that the battery life could be prolonged. To achieve this goal, in this paper we propose a security efficient group key agreement protocol based on Burmester-Desmedt （BD） scheme and layer-cluster group model, referred to as LCKM-BD, which is appropriate for large mobile ad hoe networks. In the layer-cluster group model, BD scheme is employed to establish group key, which can not only meet security demands of mobile ad hoc networks but also improve executing performance. Finally, the proposed protocol LCKM-BD are compared with BD, TGDH （tree-based group Diffe-Hellman）, and GDH （group Diffie-Hellman） group key agreement protocols. The analysis results show that our protocol can significantly decrease both the computational overhead and communication costs with respect to these comparable protocols.

Multipath Grid-Based Enabled Geographic Routing for Wireless Sensor Networks

This work proposes an efficient disjoint multipath geographic routing algorithm for dense wireless sensor networks (WSN), called Multipath Grid-based Enabled Geographic Routing (MGEGR). The proposed algorithm relies on the construction of a 2-D logical grid in the geographical region of deployment. The objective of the proposed scheme is to determine optimal or near-optimal (within a defined constant) multiple disjoint paths (multipath) from a source node to the sink, in order to enhance the reliability of the network. The determined multiple disjoint paths would be used by the source node in a round-robin way to balance the traffic across the disjoint paths, and to avoid discovered paths with cell holes. The proposed scheme limits the use of broadcasting to the process of gateway election within each cell, and the process of maintaining the table of neighbors of each gateway. Our simulation results show the effectiveness and scalability of our routing scheme with increased network size compared to on-demand routing protocols.

Destination Based Stable Clustering Algorithm and Routing for VANET

Now in modern telecommunication, one of the big topic research is a Vehicle Ad-hoc Network “VANET” (V2V). This topic is one of an “issues of the day” because research has problematic topic due to its many application-questions, what we need to solve: avoid collisions, any accidents on a way, and notifications about congestions on the road, available car parking, road-side commercial-business ads, and etcetera. These like application forms creating big delay constraining’s i.e. the instant data should reach the destination within certain time limits. Therefore, we need a really efficient stable clustering method and routing in vehicle ad-hoc network which will be resistant to network delays and meets network requirements. The methods are proposed in the paper for optimization VANETs data traffic as well as to minimizing delay. First, here is presented, a stable clustering algorithm based on the destination, contextually take into consideration various physical parameters for cluster formation such as location of the vehicle and its direction, vehicle speed and destination, as well as a possible list of interests of the vehicle. And also the next main process is to depend on these “five parameters” we can calculate the “Cluster Head Eligibility” of each car. Second, based on this “Cluster Head Eligibility”, described cluster head selection method. Third, for efficient communication between clusters, present a routing protocol based on the “destination”, which considered an efficient selecting method of next forwarding nodes, which is calculated by using “FE” metric.

Ad-Hoc网络中一种基于簇的故障诊断算法

对ad hoc网络中移动节点的故障诊断问题进行了研究,提出应用于分级ad hoc网络中的'基于簇的比较诊断算法'·'基于簇的比较诊断算法'针对'基于比较的故障诊断算法'系统开销大、在诊断期间网络拓扑变化时部分节点无法诊断的缺陷,利用簇首对诊断过程的集中控制功能,减小了诊断过程的系统开销,并突破了诊断期间要求网络拓扑不变的限制·仿真实验表明,基于簇的比较诊断算法比基于比较的故障诊断算法具有更好的性能和更小的系统开销·

空基与星基组合监视系统中的ADS-B分群算法

广播式自动相关监视(ADS-B)技术是未来航空监视技术的发展方向之一。为了满足未来空域中移动节点快速多变以及覆盖范围不断扩大等的监视需求,需要将甚高频自组织数据链和卫星数据链综合实现空基与星基组合监视系统,而分群是实现该系统的一种有效手段。为此,文中提出了一种新型的ADS-B分群算法,通过结合最大连通度准则和非确定性算法,改进了分群组网结构,提高了组网的初始收敛速度、网络整体结构的稳定性以及通信效率。

Collision Resolution MAC Protocols for Wireless Ad Hoc Networks

In wireless ad hoc networks, nodes cooperatively form a network without any infrastructure such as a BS/AP (base station or access point). The widely-used contention-based MAC protocol, IEEE 802.11b, is inefficient in multi-hop networks due to the hidden and exposed terminal problems. The most popular schedule-based MAC protocol, TDMA (time division multiple access), is difficult to implement in an ad hoc network due to the lack of infrastructure. The contribution of this paper is to provide the community novel and efficient MAC (medium access control) protocols (i.e., a collision resolution protocol) for a wireless ad hoc network without a centralized infrastructure. We propose two new MAC protocols (one distributed algorithm and one cluster-based algorithm) that use a collision resolution scheme for a network with a single BS/AP. We first compare the performance of our distributed algorithm with our cluster-based algorithm. Then, we compare our algorithm that performs better (i.e., our cluster-based algorithm) to TDMA in a two-hop network. The simulation results illustrate that our cluster-based algorithm provides higher throughput and lower delay than TDMA in a two-hop network.

Ad hoc网络中一种基于权值的分簇算法

adhoc网络是一种多跳、自组织网络.网络中的无线节点无规律的移动,使得网络的路由选择、QoS保障等问题面临新的难题.网络分层管理体系为解决这些难题提供了一种有效的手段.Adhoc网络逐渐呈现分级化的趋势.本文提出了一种基于权值的分簇算法,并通过仿真测试证明了这种方法的有效性.

Ad Hoc网络中一种基于权值的分簇算法

Ad Hoc网络是一种多跳的自组织网络,网络是由移动的节点组成。Ad Hoc网络的许多应用都依赖层次结构的支持,簇结构是Ad Hoc网络中应用最为广泛的层次结构,而这种层次结构的形成和维护依赖于某种分簇算法。提出了一种新的基于权值的分簇算法(NWBCA),该算法考虑了移动节点的最佳连接度和电池能量两个因素,通过对算法进行分析和仿真测试,证明了该算法的有效性。

一个应用于移动Ad Hoc网络管理的簇生成算法

移动Ad hoc网络(mobile Ad hoc network,简称MANET)作为一种新型移动无线通信网,与其他通信网络相比独有的特性增加了网络管理的难度.目前对MANET网络管理的研究处于起步阶段,一些标准尚未制定,而且像存在单向链路和节点的相对移动性这类问题也在研究中被忽视.为此,提出了一个利用令牌机制与最小节点标识相结合,适用于层次性管理结构的基于图的MANET簇生成算法,以及对MIB(management information base)的建议性改进.算法充分考虑了网络存在的单向链路和节点的相对移动性,提高了网络管理的灵活性和可扩展性,为MANET的网络管理提出了一种新方法.

基于位置信息的自适应Ad Hoc路由协议

传统的基于位置信息的路由算法往往采用分布式预测机制,可靠性不高,特别当源节点不知道目的节点位置时只能采用洪泛策略,增大了通信开销。本文提出一种基于位置信息的自适应路由机制LAAR(Location-based A-daptive Ad hoc Routing)。LAAR采用分层的体系结构获得全网一致的拓扑视图,消除分布式预测带来的不确定性,通过路由前的位置查询避免洪泛。LAAR综合利用多种位置更新机制,在限制网络开销的同时保障位置信息的准确性。LAAR的自适应调节机制将节点的运动状态与路由发现过程结合,实现对目的节点的动态跟踪,提高路由性能。仿真结果表明,随着节点移动速度的增加,LAAR能够获得比LAR更小的控制开销;同时在节点密度较大情况下,LAAR能获得更高的分组投递率。

分级ad hoc网络中的一种应用层故障诊断算法

针对应用层故障提出了一种故障诊断算法--"基于簇的比较诊断算法",该算法在分级adhoc网络中利用簇首对簇内节点的集中控制功能优化了诊断过程,实现了诊断期间网络拓扑变化时对移动节点的诊断。证明了算法的正确性,并分析了算法的性能。仿真结果表明,该算法突破了"基于比较的故障诊断"在诊断过程中网络拓扑不能发生变化的限制,大大减小了"基于比较的故障诊断算法"由于诊断消息的洪泛导致的大量的系统开销。

基于战场通信环境多频分级移动Ad Hoc网络结构的研究

阐述了Ad Hoc网络的国内外研究现状及在军事领域的应用情况,并在此基础上对移动Ad Hoc网络的结构进行了分析。由于现代战场通信环境的复杂性、战争节奏的加快以及侦查、制导武器系统的发展,给现代通信网络带来了严重的生存威胁,因此,基于战场环境提出了一种多频分级Ad Hoc网络结构,从而对提高我军战术通信网的抗毁能力具有一定的实用价值。

SDSR——Adhoc网络中安全的动态源路由协议

首先回顾了Ad hoc安全路由协议的研究现状,然后对于DSR协议给出一种安全路由协议SDSR。利用基于身份的密码体制节点可以非交互地共享一对称密钥,邻居节点使用该密钥进行预认证生成会话密钥。路由发现过程中采用对称密钥算法进行逐跳加密和认证,可以阻止非法节点参与路由过程,而且具有较高的效率。

基于流的AD Hoc网络接入公平性分析与研究

在Ad Hoc网络中,系统的不公平性会严重影响服务质量。针对该问题,提出一种以流为单位、用WFQ机制进行本地信息调度、采用交换节点信息调节退避时间的协调算法——FBFA。该算法计算节点每条流的服务指数,与邻节点进行交换,结合节点本身的信息和邻居节点的信息确定退避时间,提高系统的公平性。实验结果表明,FBFA算法兼顾了系统的局部公平性、全局公平性和吞吐量,系统公平性指数提高10%～20%。

无线Ad Hoc网络中基于时间广播的功率感知路由

提出了一种TBPR(time-based broadcasting for power-aware routing)协议.TBPR采用路由请求报文延迟发送机制,并通过比较路径中的累计功率消耗,选择能量消耗较低的路由,以降低网络的能量消耗,延长网络的生存周期.计算机仿真实验表明,TBPR能够取得较好的节能效果,并降低无线AdHoc网络中的能量消耗.

Ad hoc分层结构中的神经元聚类分簇算法

目前移动Ad hoc的分簇算法大都自适应能力不强,不能够满足条件受限的野外环境。该文通过利用神经元和移动结点的相似性,结合神经网络的竞争学习和模糊数学中的聚类分析,设计了一种基于神经网络和模糊数学的新型分簇算法。这是一种高效的、自适应的路由算法,具有一定的创新性,对于探讨Ad hoc网络有着重要的意义。该文首先介绍了Ad hoc网络概念和特点,然后分析了几种现存的分簇算法。接着深入研究了这种基于自组织神经网络中的竞争学习和聚类分析的混合算法。最后指出了需要改进的方面。

认知Ad hoc网络中基于市场的三级频谱分配方案

分簇是Ad hoc网络规模较大时采用的主要结构,而频谱分配是Ad hoc网络的关键技术之一。该文针对认知无线电环境的分簇Ad hoc网络,提出了一种新的基于市场的频谱分配方案,该方案中簇首节点依据业务比例从频谱管理中心购买频谱,簇内采用基于供需市场理论的频谱分配算法。分析了簇内频谱市场的两种迭代定价算法额外需求迭代算法和连续松弛迭代算法以及簇首需求订购的过程。该方案能实现各簇收益的最大化,簇首基于需求的频谱购买相对于等量购买进一步提高了频谱效用。仿真结果表明这种频谱分配方案能有效提高系统频谱效用,额外需求迭代算法和连续松弛迭代算法均表现出良好的收敛性能。

移动Ad Hoc网络覆盖节点聚集问题研究

移动Ad Hoc网络和p2p覆盖网络技术的结合是一个引人瞩目的方向,覆盖网络拓扑构造是其中的关键问题。本文提出基于拓扑匹配的移动Ad Hoc网络覆盖节点聚集模型,给出一种分布式的贪婪启发式算法,避免了热点和瓶颈问题,保证了拓扑匹配的覆盖结构的相对稳定性。仿真结果表明,该算法在不增加开销的情况下,确保生成权和极大的覆盖代理的同时也建立了拓扑匹配的聚集,因此能有效地用于基于覆盖网络的Ad Hoc路由设计中。